Spark plug



P. P. ALEXANDER Sept. 1 l, 1928.

SPARK PLUG Filed ook. 14. 1920 A'l-FORN EY Patented Sept. 11, 1928.

reunir ALEXANDER, or WORCESTER.' MASSACHUSETTS. a

. ySPARK PLUG.

Applicationfled October 14, 1,920. .'Seral N'o, 416888. i

This invention relates to spark: plug, and

the object is'to provide means .tor producing n plug, one ormorefsparkgaps withinl or near an additional spark gap,in addition tothat produced at or nearthe'end `of the usual bushing havingcommunication with the, enginecylinder. s

`A further .object toyprloduce, a spark the end, tot' thefbushing yprojecting intoV the engine cylinder, and an additional spark gap at,`the outer `end of the plug, the elec-` u trodes being :formed andmountedin-a par# ticular and novel mannenand, being inclos'ed in achamber the wallls of which are'transparent, permitting the- .operatorto inform` himself of thepcolndition of the ignition `system and tomakeany'adjustinent necessary by varyingthelgapbetweeii the electrodes.`Av still furtheryobject tok provide in connection with an additional airof electrodes,

located within a chamber,"t `ie Walls of which areti'anspai'ent,means,for permitting of the circulation of air` withinthe"chamberf` f A still further object is to provide aparticular form oicleaning device. p

A still fur her object' is to provide lor' mounting the lower electrodeor electrodes within a tubular elementwhich in turn is carried by abushing threaded into the main bushing, said electrodes merging into astem affording means for connecting the suppleuientary spark Gap' deviceto the plug per se,'and constituting one of the terminals of thesupplementary spark gap.

A still further object is to provide particular means for forming thechamber for the supplementary spark gap, and for mounting the outer orupper electrode.

With the foregoing and other.4 objects inview, the invention consists inthe novel construction, combination and arrangement of elementshereinafter described and claimed.

In the drawings, Figure l is a view of the plug in sideelevation; Figure2 is a vertical section; Figure 3 is a horizontal section, on line 3-3of Figure 2'; Figure 4 is a vertical section of another form.

The lower bushing, which in this instance will be termed a casing, isdesignated l0, and includes a threaded portion 11, for connection withthe usual threaded opening for the spark plug'inrthe cylinder wall. Thiscasing 10 is further provided with a threaded portion 12 at its upperend, this being an internal thread vand the exterior vwall being ofhexagonal form as illustrated.

A bushing 14` Ais lprovided with an eirterioi thread 15,cooperating`withthe internal thread just mentioned, and y extending through thisbushing 14, is an insulated ele-` vnient 17, constituting a stem and.either ter minating in the electrode 18, or serving to mount the latter.It is obviousl thatsoneor more contact points may be provided for`cooperationwith the cooperating electrodes,

inner electrode or electrodes just mentioned are"` preferably located ata-reasonable tance within the bore ofthe bushing. The heat developed atthis point is, not therefore colstituting the wall of thebushin'g; c Thedisadded Ito the normal heat ofpthec'ylinden due to ltlie explosion.

The stem `17 may be surrounded Awith insii lation 16 of mica or othermaterial, and a .fiber washer or washers 20 surround 4this body of micainsulation; The hexagonal portion 21serves the usual purpose of thattorml of exterior constructionand a copper4 washer 22 may be locatedimmediately below the'hexagonfa element.' Y

` The upper end of the stem The stem 17 may be tapered, `as

v 1 a a l n 17V pro'ects through afibre disk-23and is engaged ya shownat 25, in order to snugly fit the tubu- ,Y

lar member in which it is mounted.

An upper vdisk of fibre is shown at 27, and

is spaced vfrom the disk previously mentioned by tubes 28 through whichthe screws orlthreaded pins 29 pass, the headsof the pins engaging ametallic ring 30, and the lower ends of the pins engaging a metallicl yring 32.

Y An insulating body ing is formed with t 33 constituting a bush e upperdisk and upper metallic ring and receives the tubular mem- 'ber orsleeve 35, into which the upper electrode or terminal 36 is threaded.Means are therefore provided for varying the gap between the upper pairof electrodes, forpurposes well known. A nut 37 surrounds the upperterminal, and likewisea thumb nut 38.

The supplemental or additional spark gap chamber is ofparticular-importance, `and is formed by the upper and lower disksspaced as indicated, the outer wall of the chamber being formed by atubular transparent elementV 40, which is loosely retained between theupper and lower disks, permitting air to enter the chamber and adding tothe eectiveness of the device. A blue flame high lIn the formV shown inFigure 4, the bush-y ingl 1,4 `is provided with an enlarged bore 42,

lievi' g arreduced end' 43,r and this bore receives the coiled spring 44bearing against the shoulder' formed by the reduced end,and bearingagainsta fibre washer 45. Other fibre Washers 46, 47, are interposedbetween .,.fwasher l5 and ring 32'. Within the bore 42 I mounta'plunger48 having a flanged end 49 cooperating with the seat 50 on the lowerendofbu'shing MQ `The stem 1T passes through the plunger and is rigidtherewith, i, insulation being provided at 17".

'end of the stem extends into the supplemental spark gap chambeiyas inthe lnfeviousr 1nstance,is secured nut 24', and serves as one of theterminals for the additional sparky t sep engine cylinder, the plunger48 is drawn inwardly against the action of the spring, andl a smallquantityof air rushesy into: the

yfcy'lii'ider, but a. sufficient`quantity to effec-,

tively ,cleans theterminals, and act in a eertaindegree as a'coolingagent, priortothe condition.

The uppery `O11 the suctionlstroke of the piston in the production ofthe"v spark, thefefectof which is increased, in view of the additionalsupply of oxygen. The individual parts of the plug` 'can be replaced,thereby reducing to a minimum the cost of keeping the plugs in goodModifications in construction may be made within the scope of the appended claim.

Whatis claimed is y In a spark plug, including a stem for mounting acentral electrode, upper' and lower insulating disks, sleeves `forspacing said disks apart,` devices passing through said disks andsleeves for connecting the disks to form a chamber, a tubular member oftransparent material mounted between said disks and betweenthesleeves,the "tubu` lar member being shorter vthanthe sleeves, providing spacefor the admission of air to the tubularmember, and `the stem projectinginto said member, an insulating body connected with the upper insulatingdisk,y this disk constituting a flanged portion of the body and abuttingthe ends of the sleeves and extending across the endY of the tubularmember, ay threaded :sleeve carried by the insulating body, an yupperelectrode threaded into the sleeve and cooperating with the up-,t perend of the stem for forming a supplementary spark gap, and clampingdevices carried by the upper electrode. l

In testimony whereof I aiix my signature.

PAUL' P; ALEXANDER.

